There is a need in manufacturing operations for durable and reconfigurable workholding fixtures especially for flexible manufacturing operations. The fixtures must be readily and accurately adaptable to hold different workpiece shapes for machining applications or the like. Sometimes the workpieces are similar or related part shapes such as cast aluminum cylinder heads for different engines. In other manufacturing situations the parts may be of unrelated design but requiring similar manufacturing operations. In these varied applications, the fixture reconfiguration or changeover from one part design to another has to be fast enough to meet the productivity requirements of current manufacturing systems.
Magnetic chucks have been available for holding some magnetic workpieces. For example, magnetic chucks providing flat holding surfaces are commercially available under the trade designation “Quadsystem” by Technomagnete S.p.a. These chucks are provided with a plurality of magnetic pole pieces often arranged in a rectangular grid on a base plate within peripheral walls. Apart from the coils that energize or de-energize the steel pole pieces, the chuck also includes high energy permanent magnets (neodymium-iron-boron magnets) interspersed among the poles. U.S. Pat. Nos. 4,847,582 and 4,956,625 appear to describe such flat surface chucks. Suitably placed and oriented electrical coils permit the chuck to be magnetized to different levels and demagnetized for locating, securing and removing a magnetizable work piece. However, this chuck has not proven useful for securing and machining non-magnetic workpieces such as, e.g., cast aluminum alloys.
It is an object of this invention to provide a fixture utilizing a magnetic chuck for workpieces, especially non-magnetic workpieces. It is a more specific object of this invention to provide an easily reconfigured workpiece holding fixture comprising a magnetic base and modular workpiece supporting, locating and clamping elements.